No abstract

The present work is focused on the possible relationship between nitric oxide and the induction of proline in response to salt stress. The plants were subjected to 100 mM NaCl and sodium nitroprusside (SNP; the donor of NO) at different concentrations. The plants showed lower NaCl-induced oxidative stress and proline accumulation after application of low concentrations of SNP together with the NaCl treatment. The reduction in the proline content was related to increased activity of proline dehydrogenase. These results suggest that the NO could be capable of mitigating damage associated with salt stress.Additional key words: ornithine-δ-aminotransferase, proline dehydrogenase, ∆ 1 -pyrroline-5-carboxylate synthetase, sodium nitroprusside.

Nitrate plays a major role in the yield and quality of tobacco plants. This work explored the nitrogen-use efficiency (NUE) and how it can be affected by grafting. Two experiments were designed: in the first, using six commercial tobacco cultivars, the best cultivar for the NUE was selected and analysed for foliar NO 3 − content, total N, nicotine and nitrate reductase (NR) activity. The results showed the cultivar H-20 to have the best performance on NUE. It was further featured by the highest NR activity and total N and by the lowest NO 3 − and nicotine content, resulting in the highest foliar leaf biomass production and quality. In the second experiment it was tested whether the cultivar H-20 could be used as rootstock to improve the NUE of the other cultivars under study. The results showed that the grafted plants had improved the NO 3 − assimilation with respect to non-grafted plants. Hence grafting tobacco plants can be used as a quick and effective method to improve NUE, which has beneficial implications for human health and for a reduction in environmental pollution.

Methionine is a rate-limiting amino-acid for protein synthesis but non-proteinogenic roles on lipid metabolism and oxidative stress have been demonstrated. Contrary to rodents where a dietary methionine deficiency led to a lower adiposity, an increased lipid accretion rate has been reported in growing pigs fed a methionine deficient diet. This study aimed to clarify the effects of a dietary methionine deficiency on different aspects of tissue lipid metabolism and anti-oxidant pathways in young pigs. Post-weaned pigs (9.8 kg initial body weight) were restrictively-fed diets providing either an adequate (CTRL) or a deficient methionine supply (MD) during 10 days (n=6 per group). At the end of the feeding trial, pigs fed the MD diet had higher lipid content in subcutaneous adipose tissue. Expression levels of genes involved in glucose uptake, lipogenesis but also lipolysis, and activities of NADPH enzyme suppliers were generally higher in subcutaneous and perirenal adipose tissues of MD pigs, suggesting an increased lipid turnover in those pigs. Activities of the anti-oxidant enzymes superoxide dismutase, catalase and glutathione reductase were increased in adipose tissues and muscle of MD pigs. Expression level and activity of the glutathione peroxidase were also higher in liver of MD pigs, but hepatic contents in the reduced and oxidized forms of glutathione and glutathione reductase activity were lower compared with control pigs. In plasma, superoxide dismutase activity was higher but total anti-oxidant power was lower in MD pigs. These results show that a dietary methionine deficiency resulted in increased levels of lipogenesis and lipolytic indicators in porcine adipose tissues. Decreased glutathione content in the liver and coordinated increase of enzymatic antioxidant activities in adipose tissues altered the cellular redox status of young pigs fed a methionine-deficient diet. These findings illustrate that a rapidly growing animal differently adapts tissue metabolisms when facing an insufficient methionine supply.